31163921 has 2 divisors, whose sum is σ = 31163922. Its totient is φ = 31163920.

The previous prime is 31163887. The next prime is 31163969. The reversal of 31163921 is 12936113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23814400 + 7349521 = 4880^2 + 2711^2 .

It is an emirp because it is prime and its reverse (12936113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31163921 - 2¹⁸ = 30901777 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (31163221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15581960 + 15581961.

It is an arithmetic number, because the mean of its divisors is an integer number (15581961).

Almost surely, 2^31163921 is an apocalyptic number.

It is an amenable number.

31163921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31163921 is an equidigital number, since it uses as much as digits as its factorization.

31163921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 972, while the sum is 26.

The square root of 31163921 is about 5582.4654947433. The cubic root of 31163921 is about 314.6907892059.

The spelling of 31163921 in words is "thirty-one million, one hundred sixty-three thousand, nine hundred twenty-one".